U.S. patent number 6,747,989 [Application Number 09/551,430] was granted by the patent office on 2004-06-08 for method and arrangement for transmitting multimedia-related information in a packet-switched cellular radio network with external connection.
This patent grant is currently assigned to Nokia Mobile Phones, Ltd.. Invention is credited to Jarkko Sevanto.
United States Patent |
6,747,989 |
Sevanto |
June 8, 2004 |
Method and arrangement for transmitting multimedia-related
information in a packet-switched cellular radio network with
external connection
Abstract
A method is provided for transmitting multimedia-related
information between a terminal and a network device. A first
protocol stack (201, 202, 203, 204, 205, 206, 207) is defined for
the terminal and a second protocol stack (271, 272, 273, 274, 275)
is defined for the network device. The protocol stacks consist of
layers and serve the arranging of the mutual exchange of
information between the terminal and the network device. A second
network device intermediates the transmission of multimedia-related
information. An octet stream protocol layer (206, 255) is defined
for the transmission of unstructured octet streams as a certain
layer in the terminal protocol stack and a certain layer in the
second network device's protocol stack, and a network transmission
protocol layer (264, 274) is defined for the transmission of data
between the network devices. A multimedia messaging transport
protocol layer (207, 275) is also defined as a certain layer above
the octet stream protocol layer (206) in the terminal's protocol
stack and the network transmission protocol layer (274) in the
first network device. Multimedia-related information is exchanged
between the multimedia messaging transport protocol layer (207) in
the terminal and the multimedia messaging transport protocol layer
(275) in the first network device through the use of the octet
stream protocol layer (206, 255), the network transmission protocol
layer (264, 274) as well as other lower layers in the protocol
stacks.
Inventors: |
Sevanto; Jarkko (Helsinki,
FI) |
Assignee: |
Nokia Mobile Phones, Ltd.
(Espoo, FI)
|
Family
ID: |
8554466 |
Appl.
No.: |
09/551,430 |
Filed: |
April 18, 2000 |
Foreign Application Priority Data
Current U.S.
Class: |
370/466;
370/469 |
Current CPC
Class: |
H04L
29/06 (20130101); H04W 4/12 (20130101); H04W
88/184 (20130101); H04W 92/24 (20130101); H04L
69/32 (20130101); H04L 69/326 (20130101) |
Current International
Class: |
H04L
29/06 (20060101); H04Q 7/22 (20060101); H04L
29/08 (20060101); H04Q 007/22 () |
Field of
Search: |
;370/328,338,401,466,469,310,464,465 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
WO 99/61966 |
|
Dec 1999 |
|
WO |
|
WO 99/66746 |
|
Dec 1999 |
|
WO |
|
Primary Examiner: Pham; Chi
Assistant Examiner: Ferris; Derrick W.
Attorney, Agent or Firm: Perman & Green, LLP
Claims
What is claimed is:
1. A method for transmitting multimedia-related information between
a terminal arrangement and a first network device arrangement,
comprising the steps of: defining a first protocol stack for the
terminal arrangement and a second protocol stack for the first
network device arrangement, the protocol stacks consisting of
layers, for arranging the mutual exchange of information between
the terminal arrangement and the network device arrangement,
defining a third protocol stack for a second network device
arrangement, the protocol stack consisting of layers, for using the
second network device arrangement as an intermediate device taking
part in the mutual exchange of information between the terminal
arrangement and the first network device arrangement, defining an
octet stream protocol layer for the transmission of unstructured
octet streams as a certain layer in the first protocol stack and a
certain layer in the third protocol stack, defining a network
transmission protocol layer for the transmission of data between
the first network device arrangement and the second network device
arrangement, defining a multimedia messaging transport protocol
layer as a certain layer above said octet stream protocol layer in
the first protocol stack and above said network transmission
protocol layer in the second protocol stack and exchanging
multimedia-related information between the multimedia messaging
transport protocol layer in the terminal arrangement and the
multimedia messaging transport protocol layer in the first network
device arrangement through the use of the octet stream protocol
layer as well as other lower layers in the first and third protocol
stacks and through the use of said network transmission protocol
layer as well as other lower layers in the second and third
protocol stacks.
2. A method according to claim 1, comprising the step of defining a
default PDP Context between the terminal arrangement and the second
network device arrangement for the exchange of multimedia-related
information, said default PDP Context being of a specific type
defined for the exchange of multimedia-related information and
existing without explicit PDP Context activation.
3. A method according to claim 1, comprising the step of activating
a PDP Context between the terminal arrangement and the second
network device arrangement for the exchange of multimedia-related
information, said PDP Context being of a specific type defined for
the exchange of multimedia-related information.
4. A method according to claim 3, wherein the activation of the PDP
Context involves the transmission of an Activate PDP Context
message comprising a Network Service Access Point Identifier for
identifying the PDP context to be activated, a PDP Type value for
identifying the protocol as an octet stream protocol and for
identifying the service being used as the transmission of
multimedia-related information, an Access Point Name for
identifying the second network device arrangement as the intended
recipient device of the Activate PDP Context message, a QoS
Requested field for indicating the requested quality of service for
the PDP context to be activated and a PDP Configuration Options
field for identifying the first network device arrangement as the
intended peer in the transmission of multimedia-related information
as well as for carrying other information related to the PDP
context to be activated.
5. A first network device arrangement for exchanging
multimedia-related information with a terminal arrangement and a
second network device arrangement, said first network device
comprising a control entity which is arranged to implement a
protocol stack, implement a network transmission protocol layer in
the protocol stack for arranging the mutual exchange of information
between the first network device arrangement and the second network
device, implement an octet stream protocol layer for the
transmission of unstructured octet streams between the first
network device arrangement and the terminal arrangement, convert
multimedia-related information coming from the second network
device arrangement through said network transmission protocol layer
into a format to be transmitted to the terminal arrangement through
said octet stream protocol layer and convert multimedia-related
information coming from the terminal arrangement through said octet
stream protocol layer into a format to be transmitted to the second
network device arrangement through said network transmission
protocol layer.
Description
TECHNOLOGICAL FIELD
The invention concerns generally the use of certain protocols and
services for conveying certain types of information between the
different nodes of a telecommunication network. Especially the
invention concerns the transmission of multimedia-related
information between a terminal of a cellular radio network and a
store-and-forward type messaging center which has a network
connection to at least one node computer of a fixed packet-switched
network.
BACKGROUND OF THE INVENTION
Multimedia is generally understood as the synchronized presentation
of audiovisual objects to a user. It is typical to
multimedia-related information that it may contain elements of
highly different nature, like text, still images, simple graphical
elements, video and sound.
MMS or Multimedia Messaging Service is a proposed way for arranging
the delivery of messages containing multimedia-related information
from one telecommunication device to another. With
"multimedia-related" information we mean both the actual payload
data that represents presentable objects and the control
information that tells a presentation device how to handle the
payload data. According to the proposals, MMS should be applicable
for conveying such messages to and from the terminals of
packet-switched cellular radio networks such as GPRS (General
Packet Radio Service) and the packet-switched parts of UMTS
(Universal Mobile Telecommunication System) in a store-and-forward
manner much like the SMS (Short Messaging Service) text messages
are conveyed in the second generation digital cellular networks,
e.g. GSM (Global System for Mobile telecommunications).
FIG. 1 illustrates some system aspects of a known proposal for
arranging the transmission of MMS messages between two mobile
terminals 101 and 102. In FIG. 1 each terminal is operating in a
cellular telephone system of its own: terminal 101 is a UMTS
terminal operating in a UMTS network 103 and terminal 102 is an
enhanced GSM terminal operating in an enhanced GSM network 104.
From both networks there is a connection to a GPRS network 105. The
UMTS network 103 comprises a UTRAN or UMTS Terrestrial Radio Access
Network 106 as well as a CN or Core Network 107. In the enhanced
GSM network 104 a BSS or Base Station Subsystem 108 and an MSC or a
Mobile Switching Centre 109 are shown. The detailed structure of
the network elements is unessential to the present invention, but
it is known that for example a UTRAN consists of a number of Radio
Network Subsystems, each of which in turn comprises a Radio Network
Controller and a number of Node Bs roughly corresponding to base
stations. A BSS in turn comprises a Base Station Controller and a
number of Base Transceiver Stations operating under it. Various
mixed-mode cellular telephone systems are possible; for example the
BSS 108 might operate under the same CN as the UTRAN 106. The
terminals could also be exactly similar terminals operating close
to each other in a single cell.
In FIG. 1 there is a connection both from the UTRAN 106 and from
the BSS 108 to a corresponding SGSN or Serving GPRS Support Node
110 and 111. Both of these are in turn coupled, through the GPRS
trunk lines, to a GGSN or Gateway GPRS Support Node 112 which also
operates as an MMSC or a Multimedia Messaging Service Center. In
analogy with the known SMS arrangements a terminal 101 may transmit
an MMS message by identifying both the intended recipient's
terminal 102 and the MMSC through which the message is to be
transmitted (actually the latter may even be left out if there is a
default MMSC for each terminal). A Packet Control Unit or a
corresponding functionality in the UTRAN 106 takes the MMS
transmission and routes it through the current SGSN 110 to the MMSC
112 which stores the MMS message and commences the attempts for
delivering it to the intended recipient. If there is an existing
connection to the recipient's terminal 102 the MMSC may deliver the
message through the corresponding SGSN 111 and the BSS 108 to the
terminal 102. If, however, the terminal 102 is temporarily shut
off, out of coverage or otherwise unreachable, the MMSC retries the
delivery at certain time intervals until either the message is
successfully delivered or a timeout expires indicating that the
message is obsolete and can be deleted undelivered. A positive or
negative acknowledgement, depending on the success in delivery, may
be returned to the transmitting terminal 101 if required.
A topic for discussion has been the most advantageous way of using
the lower-level protocol layers and PDP Contexts (Packet Data
Protocol) in the terminals and fixed network devices to convey the
MMS messages. Somewhere at a relatively high level in the protocol
stacks of both the terminals and the MMSC there must be an MMS-TP
(Multimedia Messaging Service--Transport Protocol) entity that uses
the services offered by the lower level protocols to convey an MMS
message first from the transmitting device to the MMSC and then
further to the receiving device. Additionally the MMS messages must
be mapped into PDP Contexts of certain type; the mapping will be
closely related to the choice of lower protocol layers under the
MMS-TP entity. We anticipate that network operators will require
the MMS messaging to be distinguishable from other forms of
packet-switched data transmission in order to arrange for a
suitable charging scheme for the MMS services.
At least three prior art solutions have been proposed for conveying
MMS messages. One of them is to have a PDP Type separately defined
for MMS, and to set up a PDP Context of that type between a
terminal and an MMSC each time an MMS message has to be conveyed in
either direction. This approach has the drawback of requiring a
considerable amount of completely new specification and
standardization work. Additionally new PDP Types are only very
reluctantly accepted to the already frozen standards. A second
proposed prior art approach is to build the MMS messaging on top of
the known IP or Internet Protocol PDP Type. The latter approach
would require the GGSNs to reserve and allocate dynamic IP
addresses to mobile users. The use of dynamic addresses is not
efficiently combined to MMS services, and in any case using the IP
PDP Type for MMS messaging would consume the scarce IP addresses
and involve the whole complexity of allocating and maintaining IP
addresses and dynamically configuring hosts. A terminal roaming in
another network should in practice always use the MMSC of its home
network, because there is no possibility of dynamically telling the
IP addresses of other MMSCs to the terminal.
A third approach has been proposed in the Finnish patent
application no. 990586 of the same applicant, which application is
not available to the public at the time of filing this application.
The third approach is based on the use of the OSP or Octet Stream
Protocol as the supporting lower-level service for the
multimedia-related information. The advantages of OSP comprise
limited overhead information, avoidance of dynamic IP address
allocation, minimal need for revision to existing specifications
and flexible addition of future enhancements. However, it has been
found out that even the use of OSP does not solve all problems
related to the arrangement of FIG. 1: the implementation of the
integrated GGSN/MMSC entity is quite complex, and the multimedia
messaging service must be directly controlled by the operator
responsible for the operation and maintenance of the fixed
packet-switched network.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a feasible
method and a corresponding arrangement for conveying MMS messages
between terminals and MMSCs. It is an additional object of the
invention that the proposed method does not require exhaustive
respecification in the framework of existing standards and
proposals. A further object of the invention is to minimize the
required protocol overhead in the MMS traffic between the terminals
and the MMSCs. An even further object of the invention is to
provide means for distinguishing the MMS traffic from other types
of packet-switched information transfer. Additionally it is an
object of the invention that the drawbacks of the above-explained
OSP solution are avoided.
The objects of the invention are met by using the OSP or Octet
Stream Protocol, known as such, to carry a data stream comprising
the required multimedia-related information, implementing the
multimedia messaging center separately from the node computers of
the fixed packet-switched network and coupling it to such a node
computer through a network connection.
The method according to the invention is characterized in that it
comprises the steps of defining an octet stream protocol layer for
the transmission of unstructured octet streams as a certain layer
in a first protocol stack and a certain layer in a third protocol
stack, defining a network transmission protocol layer for the
transmission of data between a first network device arrangement and
a second network device arrangement, defining a multimedia
messaging transport protocol layer as a certain layer above said
octet stream protocol layer in the first protocol stack and above
said network transmission protocol layer in the second protocol
stack and exchanging multimedia-related information between the
multimedia messaging transport protocol layer in a terminal
arrangement and the multimedia messaging transport protocol layer
in a first network device arrangement through the use of the octet
stream protocol layer as well as other lower layers in the first
and third protocol stacks and through the use of said network
transmission protocol layer as well as other lower layers in the
second and third protocol stacks.
Additionally the invention applies to a network device which is
characterized in that its control block is arranged to implement a
network transmission protocol layer in a protocol stack for
arranging the mutual exchange of information between network device
and another network device, implement an octet stream protocol
layer in said protocol stack for the transmission of unstructured
octet streams between the first network device arrangement and a
terminal arrangement, convert multimedia-related information coming
from the other network device arrangement through said network
transmission protocol layer into a format to be transmitted to the
terminal arrangement through said octet stream protocol layer and
convert multimedia-related information coming from the terminal
arrangement through said octet stream protocol layer into a format
to be transmitted to the other network device arrangement through
said network transmission protocol layer.
The invention resembles the above-explained third solution in that
the Octet Stream Protocol or OSP is used. However, instead of
placing the MMS-TP protocol entity directly on top of the OSP
entity in a GGSN, a conversion between OSP and some general network
protocol is set up in the GGSN and said general network protocol is
used to couple the GGSN to the MMSC, which may even very distantly
located.
A PDP Context activation procedure between a terminal and a MMSC is
required to enable the transmission of MMS messages in the
framework of OSP. The device that initiates the activation
procedure transmits an Activate PDP Context Request that contains a
set of parameters that are required to identify and define the
desired PDP Context. In the case of terminal-initiated PDP Context
activation the SGSN may need to select the appropriate GGSN on the
basis of the parameters contained within the activation request and
possibly using also previously stored information about the home
location of the terminal. On the basis of the information contained
within the activation request the GGSN directs it further to a MMSC
functionality. A multitude of network elements like routers,
firewalls and so on may take part in the transmission of messages
between the GGSN and the MMSC.
After the PDP Context setup has been accomplished, MMS messages are
conveyed as an octet stream by using either the octet mode, where
the OSP protocol entity applies a packet assembly/disassembly
function, or the block mode where no separate packet assembling or
disassembling is performed.
The invention has all the advantageous features of using OSP as the
bearer for MMS, like minimized protocol overheads, complete
separation of the MMS-related PDP Context from all other PDP
Contexts even without defining a new PDP Type and avoidance of
dynamic allocation of IP addresses. Additionally the invention
simplifies the structure and operation of the MMSC compared to the
integrated GGSN/MMSC solution and enables complete independency of
the MMSC from the GPRS or other fixed packet-switched network.
The utilization of an unstructured octet stream between a terminal
and a GGSN as well as a network connection between the GGSN and a
MMSC enables the operators to direct the MMS-carrying PDP Contexts
of desired users very freely; for example the MMSC residing in the
user's home network can be used. On the other hand, operators may
also allow any MMSCs to be used, but this may restrict the service
to the mobile-originated alternative only. In any case the control
possibilities are much more flexible than in the IP-based prior art
solutions. A terminal may even select a desired MMSC by using a
certain predefined parameter in an Activate PDP Context
Request.
BRIEF DESCRIPTION OF DRAWINGS
The novel features which are considered as characteristic of the
invention are set forth in particular in the appended claims. The
invention itself, however, both as to its construction and its
method of operation, together with additional objects and
advantages thereof, will be best understood from the following
description of specific embodiments when read in connection with
the accompanying drawings.
FIG. 1 illustrates some known system aspects of packet-switched
data transmission,
FIG. 2 illustrates an arrangement of protocol stacks according to
the invention,
FIG. 3 is a schematic illustration of a method according to the
invention,
FIG. 4 is a schematic illustration of an Activate PDP Context
Request used in association with the invention,
FIG. 5 illustrates schematically an arrangement according to the
invention and
FIG. 6 summarizes some aspects of certain protocol layers according
to the invention.
FIG. 1 has been already discussed above within the description of
prior art.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 2 illustrates an advantageous arrangement of protocol stacks
in a terminal or Mobile Station (MS), an Base Station Subsystem
(BSS), a Serving GPRS Support Node (SGSN), a Gateway GPRS Support
Node (GGSN) and a Multimedia Messaging Service Center (MMSC). The
notation refers to the application of the invention in association
with an enhanced GSM network; this should not be construed as an
implicit limitation to the applicability of the invention. In the
context of UMTS, for example, the terminal would be designated as
the UE (User Equipment) and the BSS would be substituted by one of
the network devices belonging to a UTRAN, e.g. a Node B or a Radio
Network Controller. Within the BSS or the UTRAN there may be a
specific interface unit that takes care of all data traffic to and
from such packet data networks that do not share the switching
facilities (the core networks) with the cellular telephone
systems.
The protocol layers related to the application of the invention in
the MS are, from bottom to top, Layer 1201, Medium Access Control
202, Radio Link Control 203, Logical Link Control 204, Subnetwork
Dependent Convergence Protocol 205, Octet Stream Protocol 206 and
Multimedia Messaging Service--Transport Protocol 207. Some sources
refer to some of these layers as sublayers, which has no practical
importance to the present invention. It has to be noted that the
"MS" is a general notation for the apparatus or arrangement of
apparatuses which are operative at a terminal end: one possible
"MS" arrangement is a mobile telephone or other cellular network
terminal coupled to a laptop computer, whereby for example the OSP
protocol layer 206 may reside in the mobile telephone and the
MMS-TP protocol layer 207 may reside in the laptop computer.
On the left-hand side of the BSS the three lowest layers 211, 212
and 213 are the same and on top of them there is LLC Relay layer
214 for performing the required conversions between the left-hand
and right-hand sides of the BSS. The three right-hand layers of the
BSS are, from bottom to top, Layer 1221, Frame Relay layer 222 and
BSS GPRS Protocol layer 223. In the SGSN the three lowest left-hand
side layers 231, 232 and 233 are same as on the right-hand side of
the BSS, and above them is the Logical Link Control layer 234 which
is the peer entity of the similarly named layer in the MS. On the
right-hand side of the SGSN there are the Layer 1241, Layer 2242
and Internet Protocol 243 layers. On top of the SGSN protocol stack
there is a conversion entity consisting of an SNDCP half 235 and a
GPRS Tunneling Protocol half 244.
The protocol layers on the left-hand side of the GGSN are, from
bottom to top, Layer 1251, Layer 2252, Internet Protocol 253, GPRS
Tunneling Protocol 254 and Octet Stream Protocol 255. On the
right-hand side of the GGSN are the Layer 1261 Layer 2262 and
Internet Protocol 263 layers as well as the Traffic Control
Protocol/User Datagram Protocol layer 264, which in the layer
hierarchy corresponds to the combined GTP and OSP layers on the
left-hand side. There is a two-way OSP--TCP/UDP conversion, known
as such, implemented between the left-hand side and the right-hand
side of the GGSN. The protocol layers of the MMSC are, from bottom
to top, Layer 1271, Layer 2272, Internet Protocol 273, Traffic
Control Protocol/User Datagram Protocol 274 and Multimedia
Messaging Service--Transport Protocol 275.
The use of the above-mentioned protocol layers in context of the
present invention is explained in more detail in the following,
with reference also to FIGS. 3 and 4. As an example we will use a
mobile-originated procedure for enabling the exchange of MMS
messages between a MS and a MMSC. At step 301 the MS transmits an
Activate PDP Context Request message in a way basically known as
such. In order to use said message to set up a PDP Context suitable
for MMS transmission using the OSP, the MS needs to incorporate a
certain set of parameters in the message. These parameters are
schematically illustrated in FIG. 4 and they have the following
meaning:
The Network Service Access Point Identifier or NSAPI 401 is
selected by the MS. NSAPI identifies the PDP context to be
activated within the GPRS/UMTS network. For identifying the user
the message comprises also the TLLI (Temporary Logical Link
Identity) and IMSI (International Mobile Subscriber Identity)
information elements (not shown in FIG. 4).
The PDP Type 402 shall have a two-part value. The first part 402a
shall identify the protocol as OSP, and the second part 402b shall
identify the service being used and thereby allow the SGSN to
select a GGSN that can provide the service. The two-part value of
the PDP Type field can be expressed as OSP:MMS. This is a new OSP
type that does not exist in the standards at the priority date of
this patent application but is introduced in the previous Finnish
patent application no. 990586 mentioned above.
The PDP Address field 403 is most advantageously empty.
The Access Point Name or APN 404 is selected by the MS. The
selected APN identifies the GGSN which the MS wants to use for this
context. The actual APN to be used (i.e. GGSN to be used) can be
restricted by the operator by subscription. If that is the case,
the HLR (Home Location Register) record of each user for multimedia
messaging context includes the APN that is always used for MMS
contexts. The MS may omit the APN from the Activate PDP Context
Request message if the APN is configured in the HLR. Otherwise the
user may include an APN in the message. If there is no APN in the
message and no APN is configured in the HLR, the SGSN is free to
choose any GGSN for multimedia messaging context (If Dynamic
Allocation in the visited network is allowed by the HLR
record).
The QoS Requested 405 (where QoS comes from Quality of Service) is
selected by the MS. The requested service quality comprises a
number of factors and their selection typically depends on the
desired characteristics of the MMS-TP. Of the known reliability
classes, class 2 is seen as the most advantageous, meaning
RLC&LLC retransmissions as well as the use of UDP (User
Datagram Protocol) at the GPRS backbone network. Bit rates can be
negotiated to be anything without the invention limiting their
negotiation. MMS message transmission is in general
timeinsensitive, so delay class should reflect that; long delays
are allowed. Service precedence is most advantageously high if it
indicates dropping precedence which results in few packet
losses.
The PDP Configuration Options field 406 should contain at least the
Internet hostname (or IP-address) of the MMSC, the TCP or UDP port
number the MMSC is listening to, and the type of protocol (TCP or
UDP) being used between the GGSN and the MMSC. Based on this
information the GGSN is able to set up an IP-based communication
path to the MMSC. This communication path is then used for
delivering the packets carrying multimedia-related information
between GGSN and MMSC. However, the GGSN does not need to
understand the structure or contents of these packets. Instead, the
GGSN simply relays data received from the OSP layer to this
IP-based communication path, and vice versa. The PDP Configuration
Options field 406 can also be used e.g. for informing the MMSC
about certain capabilities of the MS, such as supported
content-types etc. MS-MMSC configuration information can be
included in this information element if these are not implemented
into the MMS-TP protocol itself. If there are many choices for the
MMS-TP protocol (either totally separate protocols or different
versions of the same protocol), the PDP Configuration options can
be used for informing the MMSC which protocol(s) the MS supports on
top of OSP.
At step 302 the BSS recognizes the Activate PDP Context Request
message as concerning packet-switched services and consequently
routes it to the current SGSN in a known way. At step 303 the SGSN
selects the GGSN based on the HLR records and/or the MS-provided
APN string. At step 304 the GGSN receives the message and
recognizes from the context type that the new context is for MMS.
The GGSN selects an external MMSC element based on the APN and/or
the PDP Configuration Options field in the context activation
request at step 305. The GGSN creates an association with the
service attributes and the established tunnel (identified by TID
consisting of the user's IMSI and the NSAPI value of the PDP
context). The extension of this tunnel is the network connection
(which itself is also a tunnel) to the MMSC.
After the service has been activated and possibly some MMS-related
parameters have been configured (e.g. according to the information
delivered in the Protocol Configuration Options information
element), the GGSN sends at step 306 a PDP Context Activation
Response message via the SGSN to the MS. The reception 307 of this
message at the MS finalizes the context activation. No PDP address
need to be assigned for the context, although such an assignment is
not precluded by the invention. After that, there is a logical
tunnel in place between the MS and the MMSC, where MMS-TP protocol
messages can be delivered transparently as illustrated by block
308.
The activation of the PDP Context for transmitting MMS messages may
also take place upon the initiative of the MMSC, for example in
such a case where an MMS message has been stored for delivery to an
MS which currently does not have an active PDP Context with the
MMSC. According to the adopted practice within GPRS, the MS is
always the one to transmit the initial Activate PDP Context Request
message, but it is possible for the MMSC to indicate to the MS
through a simple signaling message that there is a stored MMS
message waiting for delivery, so that it is left to the MS's
discretion to choose the moment for activating the PDP Context by
commencing the procedures illustrated in FIG. 3. In other network
arrangements an MMSC-originating PDP Context activation (though
probably with different designations of the participating devices
and associated messages) could be nearly identical to the
MS-originating one described above. The identification information
in the activation request would then serve to identify a particular
MS instead of a SGSN-GGSN-MMSC combination, whereby the routing of
the message could involve the known inquiries to the location
registers which store the current location information of the
MS.
There exists even a possibility of allocating a fixed NSAPI to
identify a PDP Context of the OSP:MMS type, whereby an explicit PDP
Context activation between the MS and the GGSN could be completely
avoided. In such a case the occurrence of said fixed NSAPI in a
packet would immediately indicate to all the devices taking part in
the communication that the packet carries multimedia-related
information, so especially the BSS and the SGSN could arrange its
routing accordingly. The IMSI and the NSAPI together, as well as
with possible other identification information of the packet, serve
to identify the MS to which such a packet belongs. A specific APN
entry would probably be required in each user's HLR records so that
a SGSN would find the correct GGSN for each user.
FIG. 5 illustrates an arrangement according to the invention
comprising a terminal or MS (or UE) 501, a BSS or UTRAN 502, a SGSN
503, a GGSN 504 and an MMSC 505. The hardware of the terminal
comprises a radio transceiver block 512, a decoding/demultiplexing
block 513, an encoding/multiplexing block 514, a control block 515
and a user data part 516. The decoding/demultiplexing block 513 is
arranged to separate received signaling information from received
user data and to direct the former into the control block 515;
similarly the encoding/multiplexing block 514 is arranged to take
signaling information from the control block 515 and to multiplex
it for transmission with user data coming from the user data part
516. All other blocks operate under the supervision of the control
block. The control connections are shown with thinner lines than
the user data and signaling information connections. The MS
protocol stack seen in greater detail in FIG. 2 is implemented
within the control block 515 by programming the corresponding
operations into a memory in the form of machine-readable processing
instructions. If die terminal arrangement comprises a number of
separate functional entities, the control block may be understood
to consist of the control functions distributed into the physical
controlling entities of the separate devices.
The MMSC is basically a large-capacity data storage 521 with a
transmission unit 522 arranged to couple it to the Internet 541 (or
a corresponding packet data network) as well as a control unit 523
to control the setting up, maintaining and tearing down of
connections. The MMSC protocol stack seen in greater detail in FIG.
2 is implemented within the control block 523 by programming the
corresponding operations into a memory in the form of
machine-readable processing instructions.
The GGSN 504 is basically like any network-coupled computer device
with a processing unit 531 and a transmission unit 532 arranged to
couple the processing unit to the trunk lines of the GPRS network
(or a corresponding packet data network) and the Internet 541. It
may also comprise a control unit 533 to control the setting up,
maintaining and tearing down of connections, although the control
functions may be implemented as a part of the processing unit 531.
The GGSN protocol stack seen in greater detail in FIG. 2 is
implemented within the control block 533 by programming the
corresponding operations into a memory in the form of
machine-readable processing instructions.
FIG. 6 summarizes the functions of the MMS-TP, OSP and lower
protocol layers in all such protocol stacks where the MMS-TP and
OSP layers are located. Between the GGSN and the MMSC similar
functions take place through the intermediating lower layers
associated with the network connection between the devices. The
MMS-TP protocol layer 601 is arranged to indicate to the OSP layer
602 the need for setting up a OSP:MMS type PDP Context with a first
primitive 603; this primitive should contain at least the APN, QoS
Requested and PDP Configuration Options information elements
referred to above. The OSP layer 602 is in general capable of
indicating to the lower layers the need for setting up PDP
Contexts, and especially capable of indicating with a setup request
primitive 604 that a PDP Context of the OSP:MMS type should be
requested. This second primitive 604 should contain at least the
PDP Type, APN, QoS Requested and PDP Configuration Options
information elements referred to above. The lower layers are in
general capable of informing die OPS layer 602 about the completed
activation of the PDP Context with a third primitive 605, and the
OPS layer 602 is in turn capable of forwarding the same information
to the MMS-TP layer 601 in a fourth primitive 606.
During operation the MMS-TP layer 601 is arranged to exchange user
data with the OSP layer according to the arrow 607, and the OSP
layer is arranged to transmit the user data to be transmitted
further down in the protocol stack according to arrow 608 either in
the octet mode or in the block mode. The former refers to the known
use of a PAD or Packet Assembly/Disassembly function to
assemble/disassemble a number of octets into/from a single packet
for more effective transport by the underlying protocols. The block
mode refers to the bypassing of the PAD function, whereby the
MMS-TP layer 601 provides the message data to the OSP layer 602 in
blocks of octets, and each block of octets is delivered as a single
OSP PDU (Protocol Data Unit) to the underlying layers. The block
mode is regarded as more advantageous for use in association with
the invention, because each MMS message could be handled as an
independent block of octets between the MMS-TP layer 601 and the
OSP layer 602.
Tearing down of the OSP:MMS type PDP Context follows the known
procedures of tearing down PDP Contexts.
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